Medulloblastoma and Primitive Neuroectodermal Tumors: Clinical and Molecular Biological Analysis and Prognosis

ABSTRACT

Primitive neuroectodermal tumors(PNETs) and medulloblastoma are common primary malignant brain tumors of childhood. Untreated patients are proven to be fatal, but the current treatment regimens may achieve 50% to 60% cures. However, the prognosis of each individual case can not be accurately determined, because exact prognostic factors have not been established. The aim of this study was to investigate whether various factors were correlated with clinical outcome, and to understand their roles in the oncogenesis. Twenty-five patients with medulloblastoma and nine patients with supratentorial PNETs were reviewed(mean follow-up periods 25.6 months). We have investigated the prognostic value of p53 protein and other oncogene expression by immunohistochemistry and DNA analysis by flow cytometry on paraffin section of the specimen. We also studied the other prognostic factors such as clinical features, tumoral factors, and treatment modalities as well. The positive expressions of p53 protein, c-myc, and pan-ras were significantly high in these tumors. With DNA flow cytometry, 18 were aneuploid and 8 were diploid. There was no significant prognostic correlation between the immunoreactivity of p53, oncogene expression, and DNA ploidy. Only the stage of tumor(T, M stage; p=0.0002, 0.0418, respectively) and chemotherapy(p=0.0433) were correlated with their prognosis. We conclude that further special investigations should be added to justify the prognostic factors for these highly malignant tumors.